Java Networking “Connection Refused: Connect”

Question

I have been trying to get a simple networking test program to run with no results.

Server:

import java.io.*;
import java.net.*;

public class ServerT         


        

Answer 1

I had the same problem because sometimes the client started before server and, when he tried to set up the connection, it couldn't find a running server.

My first (not so elegant) solution was to stop the client for a while using the sleep method:

try {
   Thread.sleep(1000);
} 
catch (InterruptedException e) {
   e.printStackTrace();
}

I use this code just before the client connection, in your example, just before Socket sock = new Socket(HOSTNAME, PORT_NUMBER);

My second solution was based on this answer. Basically I created a method in the client class, this method tries to connect to the server and, if the connection fails, it waits two seconds before retry. This is my method:

private Socket createClientSocket(String clientName, int port){

    boolean scanning = true;
    Socket socket = null;
    int numberOfTry = 0;

    while (scanning && numberOfTry < 10){
        numberOfTry++;
        try {
            socket = new Socket(clientName, port);
            scanning = false;
        } catch (IOException e) {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException ie) {
                ie.printStackTrace();
            }
        }

    }
    return socket;
}

As you can see this method tries to create a socket for ten times, then returns a null value for socket, so be carefull and check the result.

Your code should become:

Socket sock = createClientSocket(HOSTNAME, PORT_NUMBER);
if(null == sock){ //log error... }

This solution helped me, I hope it helps you as well. ;-)